To avoid the voltage drop of the onboard power supply at every start, a Voltage Stabilization System (VSS) that adopts Maxwell’s ultracapacitors as the energy storage device has been designed and implemented by Continental’s Automotive Group. The VSS is a simple addition to the existing power network. The system is installed between the negative terminal of the battery and the chassis ground of the vehicle.
The VSS system consists of two main parts, a control unit (PEU – Power Electric Unit), and the power storage unit (ESS – Energy Storage System). The latter is actually a small battery, with two double-layer capacitors linked in series. The excess energy required for restarting the engine is stored in this unit. The PEU controls the charging of the ESS, and the utilization of the accumulated energy. Unlike in conventional cars, where the negative terminal of the battery is connected directly to the metal body of the car, in cars equipped with this Start-Stop system, the chassis connection is made by the control unit, ensuring that the power storage unit is chargeable and that the car can retrieve the energy from there.